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| author | James Hogan <james.hogan@imgtec.com> | 2017-05-02 19:41:06 +0100 |
|---|---|---|
| committer | James Hogan <james.hogan@imgtec.com> | 2017-05-02 21:11:32 +0100 |
| commit | 3a158a62da0673db918b53ac1440845a5b64fd90 (patch) | |
| tree | 6ba8e4c284d1caf5dbbc2a813dc6b214d6e097d5 /arch/metag/include | |
| parent | 8a8b56638bcac4e64cccc88bf95a0f9f4b19a2fb (diff) | |
| download | lwn-3a158a62da0673db918b53ac1440845a5b64fd90.tar.gz lwn-3a158a62da0673db918b53ac1440845a5b64fd90.zip | |
metag/uaccess: Check access_ok in strncpy_from_user
The metag implementation of strncpy_from_user() doesn't validate the src
pointer, which could allow reading of arbitrary kernel memory. Add a
short access_ok() check to prevent that.
Its still possible for it to read across the user/kernel boundary, but
it will invariably reach a NUL character after only 9 bytes, leaking
only a static kernel address being loaded into D0Re0 at the beginning of
__start, which is acceptable for the immediate fix.
Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: linux-metag@vger.kernel.org
Cc: stable@vger.kernel.org
Diffstat (limited to 'arch/metag/include')
| -rw-r--r-- | arch/metag/include/asm/uaccess.h | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/arch/metag/include/asm/uaccess.h b/arch/metag/include/asm/uaccess.h index 1e5f26d2dce8..500f1be6e0fe 100644 --- a/arch/metag/include/asm/uaccess.h +++ b/arch/metag/include/asm/uaccess.h @@ -199,8 +199,13 @@ do { \ extern long __must_check __strncpy_from_user(char *dst, const char __user *src, long count); -#define strncpy_from_user(dst, src, count) __strncpy_from_user(dst, src, count) - +static inline long +strncpy_from_user(char *dst, const char __user *src, long count) +{ + if (!access_ok(VERIFY_READ, src, 1)) + return -EFAULT; + return __strncpy_from_user(dst, src, count); +} /* * Return the size of a string (including the ending 0) * |